Paul Powell

Photoelectron spectra of metallocenes

Abstract The He(II) spectra of the unsubstituted metallocenes {M(η-C 5 H 5 ) 2 }, M  V, Cr, Mn, Fe, Co, Ni and Ru, and of {Mn(η-C 5 H 4 Me) 2 } are reported; both He(I) and He(II) spectra of some decamethylmetallocenes {M(η-C 5 Me 5 ) 2 }, where M  Mg, V, Cr, Mn, Fe, Co and Ni, are also given. Intensity changes between the He(I) and He(II) spectra are shown to provide a reliable guide to band assignment. A ligand field treatment of the decamethylmanganocene cation, including limited configuration interaction, gives values for Δ 2 , B and C ; these values are also in good agreement with the photoelectron spectra of {M(η-C 5 Me 5 ) 2 } where M  V, Cr and Fe. Overlap between the ligand and metal “ d ” band structures prevents complete assignment in the cases of Co and Ni.

Synthesis of some 1,5-cyclooctadieneruthenium(II) complexes

Abstract The polymeric, halogen-bridged complex [(diene)RuX2]n (where diene = 1,5-cyclooctadiene) reacts with acetylacetone, benzoylacetone, salicylaldehyde, 2-mercaptopyridine, 8-hydroxyquinoline and 2-mercaptobenzthiazole in hot dimethylformamide in the presence of sodium carbonate, to give chelate complexes [(diene)ruthenium(chel)2]. Two geometrical isomers of 1,5-cyclooctadiene bis(benzoylacetonato)ruthenium(II) have been characterised. Diene bis(dimethyldithiocarbamato)ruthenium(II) complexes [diene = 1,5-COD or bicyclo[2.2.1]hepta-2,5-diene] are also described.

Electrophilic substitution of methoxybenzenes by pentadienyltricarbonyliron cations

Abstract The kinetics of reactions of some open-chain pentadienyltricarbonyliron cations with 1,3-dimethoxy- and 1,3,5-trimethoxybenzene, for which observable equilibria are found, are discussed. These reactions contrast with those previously reported, which go essentially to completion.

Diene and dienyl complexes of transition elements: IV1. η5-Pentadienyltricarbonylrhenium

Abstract η 5 -Pentadienyltricarbonylrhenium has been prepared by reacting 2,4-pentadienyltributyltin with bromopentacarbonylrhenium in refluxing tetrahydrofuran.

Cationic η3-allyl-2,2′-bipyridyldicarbonylmolybdenum complexes: [(η3-C3H4R)Mo(bipy)(CO)2L]+ [BF4]-

Abstract Several complexes [(η 3 -C 3 H 4 R)Mo(bipy)(CO) 2 L] + [BF 4 ] - (R  H or Me; L  NH 3 , C 5 H 5 N, Ph 3 P, Ph 3 As, (PhO) 3 P) have been prepared from (η 3 -C 3 H 4 R)Mo(bipy)(CO) 2 Cl and AgBF 4 in acetone, followed byreaction with L. Their structures are discussed in the light of their infrared, 1 H and 13 C NMR spectra.

Diene and dienyl complexes of transition elements: VI. The protonation of two isomeric (η5-cyclopentadienyl)-(η4-1,7-diphenylheptatrien-1-one)rhodium(I) complexes

Abstract Two isomeric complexes [Rh2-5-η-PhCO(CH) 4 CHCHPh(η 5 -C 5 H 5 )] and [Rh4-7-η-PhCOCHCH(CH) 4 Ph(η 5 -C 5 H 5 )] have been prepared. The former reacts with HBF 4 to give the salt [Rh(η 3 -PhCOCH 2 (CH) 3 CHCHPh(η 5 -C 5 H 5 )] + BF 4 − in which the acyl PO group is coordinated to the metal. The latter, however, on treatment with HPF 6 , yields a η 5 -pentadienyl salt [Rhη 5 -PhCOCH 2 (CH) 5 Ph(η 5 -C 5 H 5 )] + PF 6 − . 1 H and some 13 C NMR spectra are reported.

Diene and dienyl complexes of transition elements : III. Protonation of η-cyclopentadienyl-η-dienol-rhodium and -iridium complexes: synthesis of cationic complexes containing open chain pentadienyl ligands☆

Abstract The protonation of several dienol complexes of rhodium and iridium, [M(η 4 -R 1 CHCR 2 CHCHCHOHR 3 )(η 5 -C 5 H 5 )], (M = Rh, Ir), (R 1 = Ph; R 2 = H or Me; R 3 = Bu t or Aryl) has been investigated using 1 H NMR spectroscopy. Initially the proton adds to the carbon atom of the diene system adjacent to the alcohol function to yield η 3 -enyl derivatives. Deuteration studies indicate that this addition occurs stereospecifically endo . This reaction is followed by elimination of water to afford cationic complexes, [M(η 5 -R 1 CHCH 2 CHCHCR 3 )(η 5 -C 5 H 5 )] + , which were isolated as BF 4 − or PF 6 − salts. The open chain substituted pentadienyl ligands in the cations where R 3 = Aryl adopt an unsymmetrical structure, probably cis syn anti , in contrast to the corresponding pentadienyltricarbonyl-iron derivatives, in which the ligand is symmetrical ( cis syn , syn ).

Diene and dienyl complexes of transition elements

Abstract Reaction of [M(η 4 -PhCHCRCHCHCOPh)(η 5 -C 5 H 5 )], [M = Rh or Ir; R = H or Me] with HBF 4 or HPF 6 affords the crystalline salts [M(η 3 -PhCHCRCHCH 2 -COPh)(η 5 -C 5 H 5 )]Y, [Y = BF 4 or PF 6 ], in which the acyl CO group is coordinated to the metal. HCl and HBr also protonate the dienone complexes (M = Rh) at carbon, giving the covalent derivatives [RhX(η 3 -PhCHCHCHCH 2 COPh)(η 5 -C 5 H 5 )], [X = Cl, Br]. A mechanism involving endo addition of H + to the η 4 -dienone ligand is in accord with deuteration studies. 1 H and 13 C NMR spectra of the new complexes are discussed. The reactions of [Rh(η 4 -PhCHCHCHCHPh)-(η 5 -C 5 H 5 )] with HCl and HBr are also reported.

Syntheses and structure of pseudooctahedral molybdenum-η3-hexadienyl complexes

Compounds of the type [MoX(η3-C5H6Me)(CO)2(MeCN)2] where X = Cl (1) and Br (2) have been prepared by oxidative addition of 1-halohexa-2,4-dienes to Mo(CO)3(MeCN)3. Addition of the bisphosphine Ph2PCH2CH2PPh2 (dppe) or 2,2′-bipyridine (bipy) to 2 gives [MoBr(η3-C5H6Me)(CO)2(dppe)] (3) or [MoBr(η3-C5H6Me)(CO)2(bipyl)] · 12MeCN (4), respectively, in high yields. 1,10′-phenanthroline and 1 afforded the bright red complex [MoCl(η3-C5H6Me)(CO)2(phen)] (5). A crystallographic X-ray analysis showed the structure of 2 to be analogous to diether and diamine chelates previously reported. According to spectroscopic data the bisphosphine compound 3 adopts a different structure than 2.

Cationic η3-Allyl complexes of rhodium

Abstract The complexes [Rh(η 3 -C 3 H 4 R)(η 5 -C 5 R′ 5 )L] + BF 4 - (R  1-Me, R′  H, Me; R  2-Me, R′  H) (L  C 5 H 5 N, Ph 3 P, Ph 3 As) have been prepared from Rh(η 3 -C 3 H 4 R)(η 5 -C 5 R′ 5 )Cl and AGBF 4 in acetone, followed by reaction with the stoicheiometric quantity of L. The 1 H and 13 C NMR spectra of the salts are reported and discussed.